Various types of implantable sensors, such as venous oxygen saturation sensors, are becoming more readily available. Such sensors are capable of providing measures of a physiologic property, such as venous oxygen saturation, to an implanted cardiac system, so that such measures can be used as metrics of hemodynamic status, and more specifically, to monitor a patient's heart disease status. A potential problem with such implantable sensors is that they produce a large amount of data, all of which can not be efficiently stored and/or analyzed due to memory and processing constrains of implantable systems. Additionally, where there is an attempt to determine actual values of a physiologic property, such as actual values of venous oxygen saturation, the sensor and/or the sensor measurements must be calibrated from time to time. Otherwise, small inaccuracies and changes in activity and stress levels of the patients can affect the actual values of the physiologic properties that are determined. This can lead to inaccurate monitoring of a patient's heart disease, and the like. It would be beneficial if new and useful methods for using implantable sensors to monitor a patient's heart disease were provided. Preferably, such methods would not require that the implantable sensor (once implanted) be repeatedly calibrated. Additionally, it would be preferable if such methods can provide for a reduction in the amount of data the implantable system stores.